This invention relates to improved socket contacts for electrical connectors. More particularly, it relates to improved electrical sockets especially suitable for use in telecommunication and computer connectors, the sockets having greatly improved constancy of spring force per unit length of deflection of a spring means contained therein.
Electrical sockets or receptacles, as they are sometimes referred to, are essential elements of electrical connectors. Normally one end of the socket terminates a cable conductor by using solder or some other technique. The other end is open and is adapted to receive a corresponding electrical pin contact such as a wire-wrap post which is mounted in a member for completing a circuit. Socket contacts are designed to insure low and stable electrical resistance through the connector, as well as mechanical integrity for the connection. Sockets have been made to provide these features by using a stamped and formed sheet metal box with a single elliptical spring fixed in the box for providing spring force downward on the pin.
An example of such a socket is shown in U.S. Pat. No. 3,370,265 issued to Berg and assigned to Berg Electronics, Inc. The Berg patent shows a stamped and formed rectangular box receiving a cruciformed-shaped tapered elliptical spring. The spring is held in the box, in one embodiment by the use of ears on each end of the spring, and in another embodiment by lateral ears in the middle of the spring. The use of tapered elliptical springs in sockets is also taught in Mechanical Design and Systems Handbook, Section 33.31, copyrighted in 1964 by McGraw-Hill, Inc., Library of Congress Catalog No. 62-21118. One drawback to the Berg design is that in order to obtain acceptable force on the inserted pin over a range of spring deflection, Berg normally uses a beryillium copper alloy as the spring material. This alloy is expensive to use.
Another example of the use of an elliptical spring to provide mechanical and electrical contact to a pin is taught in U.S. Pat. No. 3,140,141 issued to Nava and assigned to Akzona Incorporated, assignee of the present invention. The Nava patent shows a machined socket body rather than a stamped box, as taught in Berg, and provides a single elliptical spring held in the socket body by a shroud.
Stamped sockets have also been provided which utilize spring arms extending into the cavity of the box to provide spring contact directly with the pin. Examples of such contacts are shown in U.S. Pat. No. 3,955,689 issued to Licht and assigned to the Bunker Ramo Corporation and U.S. Pat. No. 4,076,369 issued to Ostapovitch and assigned to Northern Telecom Limited. Each of these patents show socket contacts having spring arms integral with the main body of the socket, with the free ends of the arms facing inwardly towards the center of the contact.
U.S. Pat. No. 3,384,866 also issued to Nava and assigned to Akzona Incorporated, shows a socket having a spring member with a flat portion adapted to engage a corresponding electrical pin, and a pair of reversely turned arms integral with the flat portion of the spring, for providing spring pressure on the pin. As in the previously discussed Nava patent, the socket is machined rather than stamped.
It is, therefore, desirable to provide an electrical socket which is an improvement over the prior art.